It amazes me the amount of precision we can get for work like this. The entire difference between "yup, the moon definitely came from a big impact of another body with Earth" and "we think it came from impact of another body with Earth" is just a few ppm of an Oxygen isotope.

If Theia crashed into the Earth in such a way that Theia ceased to exist as independent body, wouldn't the result be an Earth-Theia hybrid? And if so, why would it be surprising that the Moon's composition matched that of the Earth after the collision? Wouldn't both the Earth and the Moon have equal "parts" of Theia in them?

The majority opinion is that the collision threw a vast amount of material out, and for many thousands of years, possibly as long as a couple of million, the earth had thick rings from it. A major question is the angle of the collision. Was it smack on, or was it more of a big sideswipe? That determines the mixing of the two. None of this is known, and may never be known.

In addition, how much water, hydrogen, and other light elements and molecules, were driven off by the collision, and immense heat, which caused the planet to remain molten from it for as long as three million years, or longer? This changes the "natural" percentages. Without knowing that too, this is still no better than guessing.

It would be very nice to have confirmation. It places Theia as the mainstream martian massed impactor, I think. And it is definitely the missing piece to dating the Moon from the late bombardment crust element buildup of Earth, which uses the impact as constraint.

Unfortunately there seems to be possible confounds:

- "... we speculate on an enstatite chondrite–like composition of Theia."

- "The observed small compositional difference could alternatively be explained by a carbonaceous chondrite–dominated late veneer."

So a late veneer with either carbonaceous or enstatite chondrites could predict the expected bulk composition respectively sample bias from Apollo surface sampling. The result is accordingly criticized, but hailed as exciting and a question solver:

"And Prof Alex Halliday of Oxford University, is among many scientists who are surprised that the difference between the Theian material found in the Moon rock and the Earth is so small.

"What you are looking for is a much bigger difference, because that is what the rest of the Solar System looks like based on meteorite measurements," he said.

Dr Herwartz measured the difference in what is called the isotopic composition of the oxygen contained in rocks on Earth and Moon rock. This is the ratio of different forms of oxygen.

Studies of meteorites from Mars and the outer solar system show that these ratios are markedly different - rather like a fingerprint. So Prof Halliday and others are puzzled by the fact that the fingerprints of Earth and Theia seem almost identical.

One possibility is that Theia was formed very close to the Earth and so had a similar composition. If that was the case, it raises the possibility that the assumption that each planet in the current Solar System has a markedly different fingerprint needs to be revisited, according to Prof Halliday.

"It raises the question of how well the meteorites from Mars and the asteroid belt in the outer Solar System are representative of the inner Solar System? We do not have samples from Mercury or Venus.

"They may well be similar to the Earth. If that is the case then all the arguments over the similarities of the Earth and the Moon fall away," he told BBC News.

Dr Mahesh Anand from the Open University described the research as "exciting" but noted that the data was from just three lunar rock samples.

"We have to be cautious about the representativeness of these rocks of the entire Moon, and so further analysis of a variety of lunar rocks is required for further confirmation," he said."

As far as I can see it looks good, provided they haven't made a mistake or the sample bias is too severe. Enstatites are believed by the expert Bill Bottke to derive from a missing "E" belt of asteroids, where some bodies later became the Hungarians. [ http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1269.pdf ] They are thus related to the late bombardment and especially its "late, late" tail, but also to Mars. Two martian sized bodies at the same time (Mars being finalized in 3-4 million years) deriving from the same disk portion seems like a simple sell.

If Theia crashed into the Earth in such a way that Theia ceased to exist as independent body, wouldn't the result be an Earth-Theia hybrid? And if so, why would it be surprising that the Moon's composition matched that of the Earth after the collision? Wouldn't both the Earth and the Moon have equal "parts" of Theia in them?

Analogously Theia, if Mars sized, contributed about 10 % of Earth mass and Tellus was remelted to form Earth. Incidentally here, "Tellus" is the proposed name for proto-Earth by geophysicists, still waiting for acceptance by their naming organization. (Geologists want to name the periods and objects right up to the fist geological objects formed as grains in the disk. I would assume astronomers would say "fair enough".) The process merits a dichotomy for both objects, Tellus-Theia collided, Earth-Moon resulted.

Yes: "Collision models peg the ratio at 70 percent to 90 percent. Herwartz suspects that it's closer to 50/50, but that’s just an informed guess at this point."

It's a very nice mass relation here: Theia was ~ 1/10 of Earth's mass, the Moon is ~ 1/10 of Theia's mass or ~ 1 % of Earth's mass. Hence the resulting Moon out of ejecta but also a 50/50 % mix (say) becomes less surprising.

We should keep in mind that the authors is suggesting a strong suggestion that the impact theory is valid, given what we know.

Until/unless there is a smoking gun, these conclusions are a result of a process of elimination that arrives to the most sensible answer to the hypothesis.

I would suggest a follow up study to obtain more samples from both Earth and the moon to see if there are variations, in case the impact by Theia on Earth did not result in a homogenous mixture and whether the lunar samples were influenced by previous impacts.

Two questions:1) If there had not been an impact, would the Earth still have sufficient internal heat to drive plate tectonics, magnetic field, etc? How does Venus compare?2) Would it have been possible for Theia to have formed on the opposite side of the Sun in approximately the same orbit as the proto-Earth? If so, that would seem to account for a similar isotopic composition.

It seems like it might be a good idea to obtain samples from Mercury and Venus to see how their isotopic composition differs.

If Theia crashed into the Earth in such a way that Theia ceased to exist as independent body, wouldn't the result be an Earth-Theia hybrid? And if so, why would it be surprising that the Moon's composition matched that of the Earth after the collision? Wouldn't both the Earth and the Moon have equal "parts" of Theia in them?

I am not a scientist, but it seems to me that since the Earth was larger than Theia, the ratio of Theia to Earth materials would be lower on Earth than on the moon. Also, it seems reasonable that the material shot out into orbit from the collision would be more Theia than Earth, because Theia was smaller than Earth and therefore would be more likely to have smashed to bits, whereas only a portion of the Earth's outer layer was scooped out and ejected into orbit.

Edit: Then again, I suppose it depends on how directly Theia hit the Earth. I'm sure the theorists have a good idea of whether it was a direct hit or a glancing blow.

Two questions:1) If there had not been an impact, would the Earth still have sufficient internal heat to drive plate tectonics, magnetic field, etc? How does Venus compare?2) Would it have been possible for Theia to have formed on the opposite side of the Sun in approximately the same orbit as the proto-Earth? If so, that would seem to account for a similar isotopic composition.

It seems like it might be a good idea to obtain samples from Mercury and Venus to see how their isotopic composition differs.

Total hearsay as I can't remember where I got this, but I heard that one theory is that plate tectonics would not have happened without the collision. The theory goes that earth (Tellus whateve) was one solid sheet of mantle/crust before the impact, and the fractures/ heat differentials introduced by the impact jump started tectonics. If anyone else has heard about this/I got this wrong, please chime in.

Two questions:1) If there had not been an impact, would the Earth still have sufficient internal heat to drive plate tectonics, magnetic field, etc? How does Venus compare?2) Would it have been possible for Theia to have formed on the opposite side of the Sun in approximately the same orbit as the proto-Earth? If so, that would seem to account for a similar isotopic composition.

It seems like it might be a good idea to obtain samples from Mercury and Venus to see how their isotopic composition differs.

Total hearsay as I can't remember where I got this, but I heard that one theory is that plate tectonics would not have happened without the collision. The theory goes that earth (Tellus whateve) was one solid sheet of mantle/crust before the impact, and the fractures/ heat differentials introduced by the impact jump started tectonics. If anyone else has heard about this/I got this wrong, please chime in.

It was news to me until NDGT said it on Cosmos. I heard it on Cosmos on Fox: it must be true .

Read about this on the BBC the other day, and there appears to be a fair degree of scepticism about the article. That's partly because the difference in O-isotope ratios is very small, and partly because, so far, only three samples have been analysed. And all of the ones we have came from the surface.

If Theia crashed into the Earth in such a way that Theia ceased to exist as independent body, wouldn't the result be an Earth-Theia hybrid? And if so, why would it be surprising that the Moon's composition matched that of the Earth after the collision? Wouldn't both the Earth and the Moon have equal "parts" of Theia in them?

I am not an astrophycisist or anything, but, well, throw a smaller ball at a larger, much heavier ball -- what happens? Yes, the smaller one bounces off the heavier one. I would assume that most of the mass of Theia just kind of bounced back in to space, along with some of Earth, and then formed the Moon.

I am not an astrophycisist or anything, but, well, throw a smaller ball at a larger, much heavier ball -- what happens? Yes, the smaller one bounces off the heavier one. I would assume that most of the mass of Theia just kind of bounced back in to space, along with some of Earth, and then formed the Moon.

Unless you are throwing balls at each other with velocities in the realm of kilometres per second, I think your anecdote is irrelevant, sorry.

If Theia crashed into the Earth in such a way that Theia ceased to exist as independent body, wouldn't the result be an Earth-Theia hybrid? And if so, why would it be surprising that the Moon's composition matched that of the Earth after the collision? Wouldn't both the Earth and the Moon have equal "parts" of Theia in them?

I am not an astrophycisist or anything, but, well, throw a smaller ball at a larger, much heavier ball -- what happens? Yes, the smaller one bounces off the heavier one. I would assume that most of the mass of Theia just kind of bounced back in to space, along with some of Earth, and then formed the Moon.

A planet that smashes into another planet doesn't bounce. This would require elastic deformation and the involved scales and speeds aren't really conductive to that.

If Theia crashed into the Earth in such a way that Theia ceased to exist as independent body, wouldn't the result be an Earth-Theia hybrid? And if so, why would it be surprising that the Moon's composition matched that of the Earth after the collision? Wouldn't both the Earth and the Moon have equal "parts" of Theia in them?

I am not an astrophycisist or anything, but, well, throw a smaller ball at a larger, much heavier ball -- what happens? Yes, the smaller one bounces off the heavier one. I would assume that most of the mass of Theia just kind of bounced back in to space, along with some of Earth, and then formed the Moon.

I can't imagine the rigidity able to withstand the incredible pressures of planet-on-planet action.

Anyhow, also in the speculative realm: if Theia were very large, and delivered a side-swiping blow to Earth, it could have torn a bunch of Earth off for the moon, while it continued its journey to the Sun or interstellar space. Or if it were smaller and hit more directly, “bouncing” as this comment suggests, might have been captured. Either way, you'd think a huge fraction of the mass would've circled BOTH residuals, making the top surfaces, perhaps miles of them, out of the same debris that eventually rained down. Given that assumption, I'd think it surprising that any difference in surface rocks would be attributable to different planetary sources.

The only way I'd expect much difference is for a significantly smaller Theia — i.e., very roughly the 80:1 ratio as the Earth's mass is to the moon — to have struck the earth with just enough force to redirect it enough to be captured in orbit, and without much debris kicked up in the process. That seems an awfully thin slice of possible ways for the moon to have formed, so the absence of differences hardly threatens the Theia hypothesis.

[PS:] If my quick math is correct, spreading the mass of the moon evenly over the earth might add another 20 miles of thickness to it (at slightly less density). So if that amount of debris resulted from a collision, we are very unlikely to have found rocks on either body that weren't just debris.

Reminds me of my geochemistry prof in college. After working with a fraction of a gram sample from one of the lunar missions, he wrote a paper titled "The Geochemistry of the Moon". Guess he was a big picture guy.

It's a very nice mass relation here: Theia was ~ 1/10 of Earth's mass, the Moon is ~ 1/10 of Theia's mass or ~ 1 % of Earth's mass. Hence the resulting Moon out of ejecta but also a 50/50 % mix (say) becomes less surprising.

I think I may have lost the original point I'm replying to in the quote chain, but someone had asked about what percent of Earth's mass came from Theia... some back-of-the-envelope math:

Say Theia had a mass of 100 units, Earth currently has a mass of 1000 units, and the moon currently has a mass of 10 unit => Tellus had a mass of 910 units (Tellus + Theia = Earth + Moon). If they collided and form the Moon (10 units) and the Earth (1000 units), and the moon is 50% Theia, 5 of Theia's 100 units are helped form the moon and the remaining 95 helped form Earth => Earth is 95/1000 = 9.5% Theia and 90.5% Tellus.

Interestingly enough, given the ratios quoted above, Earth contains somewhere between 9% [Moon is 100% Theia] and 10% [Moon is 100% Tellus] of Theia. That's a much stricter bound than I was expecting before I ran the numbers.

If Theia crashed into the Earth in such a way that Theia ceased to exist as independent body, wouldn't the result be an Earth-Theia hybrid? And if so, why would it be surprising that the Moon's composition matched that of the Earth after the collision? Wouldn't both the Earth and the Moon have equal "parts" of Theia in them?

Given the large difference in the masses of all the objects involved, the Earth and Moon likely have very different ratios of Theia:Tellus. Imagine you have a 2 liter bottle of Coke (in a pitcher so there's room to add more liquid) and a shot glass of Sprite... if you dump the Sprite into the Coke, mix it well, and pour a tumbler then the both the tumbler and the pitcher have the same Coke:Sprite ratio. However, if you pour some of the Sprite into the tumbler, top it off with some of the Coke, and then dump the rest of the shot glass into the pitcher, you'll likely have very different Coke:Sprite ratios in the two vessels. The latter is more analogous to two planets colliding and ejecting magma into space.

i always smile at moon-creation narratives. as many here point out we will likely never know to any real certainty how exactly the moon formed, but it seems sufficient to know that a mars-sized (or much smaller as suggested in this study) chunk smacked into the early earth and some portion of it and earth reeled off and stuck in orbit to form the moon.

the more interesting thought train that these discussions do bring up in my mind, however, is how the moon is related to life on earth. the moon-created tides enable heat flow from equatorial to polar regions, and the tides themselves in effect 'stir' the ocean shores, varying the salinity and thermal energies, allowing proto-life nucleic acids to form. so if, as many hypothesize, the tides created by the moon and the earth rotation created by the impact are integral to the life-enabling climate of early earth, how many orders of magnitude less likely is a planet in the life-zone of another star to generate life without a moon-like satellite? sobering.

one small step for man, one giant leap for mankind. and still the universe doesn't really care. exciting, and sobering.

[PS:] If my quick math is correct, spreading the mass of the moon evenly over the earth might add another 20 miles of thickness to it (at slightly less density). So if that amount of debris resulted from a collision, we are very unlikely to have found rocks on either body that weren't just debris.

The earth was molten before the collision, and certainly after, so I wouldn't expect that the surface would simply be a layer of Tellus-Theia collision debris. Convection would have mixed it, and heavier materials would have tended to drift toward the core just like happened with earth to begin with.

The majority opinion is that the collision threw a vast amount of material out, and for many thousands of years, possibly as long as a couple of million, the earth had thick rings from it. A major question is the angle of the collision. Was it smack on, or was it more of a big sideswipe? That determines the mixing of the two. None of this is known, and may never be known.

In addition, how much water, hydrogen, and other light elements and molecules, were driven off by the collision, and immense heat, which caused the planet to remain molten from it for as long as three million years, or longer? This changes the "natural" percentages. Without knowing that too, this is still no better than guessing.

In the first place, the isotopic RATIOS will be exposed to the same forces, meaning even if the isotopes change, the ratios won't. Since they're measuring the ratios, and not relying on a single isotopic difference, they should be the same if the origins of the materials was the same.

They're not.

How much oxygen water and hydrogen there was "driven off" doesn't matter because THEY WEREN'T IN THE ROCKS that stayed behind. The rocks are where we get the ratios of isotopes of oxygen for both bodies. Rock of a known age will yield a known isotopic ratio. This is how we determine the age of ice layers (by the isotopic ratios in the difference between them). Rocks don't absorb oxygen very well and the rate at which they do can be used to correct for variances.

Secondly, physics dictates how things happen. We have a presumptive scenario with an impact at some point between two bodies of unequal mass and a very solidly known end result at another point. Physics models fill in the rest, which gives us known ranges for the events to happen with regard to when, how much, how fast and at what angles. Now that we know for sure there were two distinct bodies, it's much easier to toss out the "it came from earth" model (which physics was having a hard time reconciling with what we have now anyhow).

Current models show that Theia formed in the Lagrange point either 60 degrees ahead of or behind the Earth in the same orbit. Which hit which can be argued, however the velocities in the impact and the mass of the moon itself, say that when they hit, the two were traveling at a nearly identical velocity (about 29km/s) in the same relative orbit (relative to each other so that they'd collide). Any other vectors or speeds would have obliterated the Earth or Theia or both, resulting in either an asteroid field (which by now would be gone), or a single, moonless planet. It's an exceptionally rare event to happen to two small, rocky bodies that results in the arrangement we have with the moon now. Cooling would have been relative quick - no more than a couple of hundred thousand years it's estimated.

(You should look at fluid dynamic models to see how little mixing occurs when two fluids of uneven densities impact each other, too. It's pretty shocking to see how long concentrations remain fixed without any other outside influences. Or you could simply float some Irish Whiskey on top of some Butterscotch Schnapps and see that at some speeds, they don't mix at all. I suggest the latter. It's educational and tasty.)

We have a specific set of conditions today that can be extrapolated back thanks to the laws of physics. Those laws say what the velocities and angles of the collision had to have been - within a very narrow range - in order to arrive at a system we have NOW. That's not "guesswork". That's science.

Back in the 1960's, when I went to grade school, much of what you wrote was then "state of the art" when it came to knowing how the moon formed. Much has changed since then with regard to computer simulations, the precision of chemical analysis and other scientific tools of detection and investigation.

This finding, and the other observations and models preceding it, explains why the Moon's composition is only slightly different from the Earths, but also proves that the moon didn't COME from the Earth. Your speculative assertions fail to take into account the science involved in what has been found to date. It would also seem, for whatever reason, you're sticking to an out-dated moon creation model.

[PS:] If my quick math is correct, spreading the mass of the moon evenly over the earth might add another 20 miles of thickness to it (at slightly less density). So if that amount of debris resulted from a collision, we are very unlikely to have found rocks on either body that weren't just debris.

The earth was molten before the collision, and certainly after, so I wouldn't expect that the surface would simply be a layer of Tellus-Theia collision debris. Convection would have mixed it, and heavier materials would have tended to drift toward the core just like happened with earth to begin with.

I have no idea how long debris would've orbited before coming back down. How would you compare it to the time for the crust to cool enough that convection would be reduced?

We should keep in mind that the authors is suggesting a strong suggestion that the impact theory is valid, given what we know.

Until/unless there is a smoking gun, these conclusions are a result of a process of elimination that arrives to the most sensible answer to the hypothesis.

I would suggest a follow up study to obtain more samples from both Earth and the moon to see if there are variations, in case the impact by Theia on Earth did not result in a homogenous mixture and whether the lunar samples were influenced by previous impacts.

Proper core samples instead of surface material would be good, preferably from more sparsely cratered regions.

The details may be fuzzy, but as Herwartz said in a statement: “we can now be reasonably sure that the giant collision took place.”

Haven't we been reasonably sure for awhile? The explanation I've heard is that, because the Moon has continued to drift away from us due to the friction of tidal gravity, if you reverse time, the Moon eventually ends up in the same position as the Earth (i.e. they collided). I don't see a good explanation for that other than a collision...

The details may be fuzzy, but as Herwartz said in a statement: “we can now be reasonably sure that the giant collision took place.”

Haven't we been reasonably sure for awhile? The explanation I've heard is that, because the Moon has continued to drift away from us due to the friction of tidal gravity, if you reverse time, the Moon eventually ends up in the same position as the Earth (i.e. they collided). I don't see a good explanation for that other than a collision...

The details may be fuzzy, but as Herwartz said in a statement: “we can now be reasonably sure that the giant collision took place.”

Haven't we been reasonably sure for awhile? The explanation I've heard is that, because the Moon has continued to drift away from us due to the friction of tidal gravity, if you reverse time, the Moon eventually ends up in the same position as the Earth (i.e. they collided). I don't see a good explanation for that other than a collision...

Maybe planets reproduce via fission?

Could have been constructed as some sort of computer to solve some sort of problem that interrupts pan-dimensional beings' (lets say mice) favorite game?

It would be very nice to have confirmation. It places Theia as the mainstream martian massed impactor, I think. And it is definitely the missing piece to dating the Moon from the late bombardment crust element buildup of Earth, which uses the impact as constraint.

Unfortunately there seems to be possible confounds:

- "... we speculate on an enstatite chondrite–like composition of Theia."

- "The observed small compositional difference could alternatively be explained by a carbonaceous chondrite–dominated late veneer."

So a late veneer with either carbonaceous or enstatite chondrites could predict the expected bulk composition respectively sample bias from Apollo surface sampling. The result is accordingly criticized, but hailed as exciting and a question solver:

"And Prof Alex Halliday of Oxford University, is among many scientists who are surprised that the difference between the Theian material found in the Moon rock and the Earth is so small.

"What you are looking for is a much bigger difference, because that is what the rest of the Solar System looks like based on meteorite measurements," he said.

Dr Herwartz measured the difference in what is called the isotopic composition of the oxygen contained in rocks on Earth and Moon rock. This is the ratio of different forms of oxygen.

Studies of meteorites from Mars and the outer solar system show that these ratios are markedly different - rather like a fingerprint. So Prof Halliday and others are puzzled by the fact that the fingerprints of Earth and Theia seem almost identical.

One possibility is that Theia was formed very close to the Earth and so had a similar composition. If that was the case, it raises the possibility that the assumption that each planet in the current Solar System has a markedly different fingerprint needs to be revisited, according to Prof Halliday.

"It raises the question of how well the meteorites from Mars and the asteroid belt in the outer Solar System are representative of the inner Solar System? We do not have samples from Mercury or Venus.

"They may well be similar to the Earth. If that is the case then all the arguments over the similarities of the Earth and the Moon fall away," he told BBC News.

Dr Mahesh Anand from the Open University described the research as "exciting" but noted that the data was from just three lunar rock samples.

"We have to be cautious about the representativeness of these rocks of the entire Moon, and so further analysis of a variety of lunar rocks is required for further confirmation," he said."

As far as I can see it looks good, provided they haven't made a mistake or the sample bias is too severe. Enstatites are believed by the expert Bill Bottke to derive from a missing "E" belt of asteroids, where some bodies later became the Hungarians. [ http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1269.pdf ] They are thus related to the late bombardment and especially its "late, late" tail, but also to Mars. Two martian sized bodies at the same time (Mars being finalized in 3-4 million years) deriving from the same disk portion seems like a simple sell.

I've never understood why this is a big question. The main driver of isotopic differences between planets is mass separation due to temperature differences (and maybe chemistry) in the protoplanetary disk. Thus what you would expect is that it is a radius related parameter. If Tellus and Thea each formed in the same orbit, as most proposals would have it, with Thea at one of Tellus' trojan points, then you would expect their isotopic signatures to be NEARLY IDENTICAL, and no surprise or any new theory should need even be mentioned.

Two questions:1) If there had not been an impact, would the Earth still have sufficient internal heat to drive plate tectonics, magnetic field, etc? How does Venus compare?2) Would it have been possible for Theia to have formed on the opposite side of the Sun in approximately the same orbit as the proto-Earth? If so, that would seem to account for a similar isotopic composition.

It seems like it might be a good idea to obtain samples from Mercury and Venus to see how their isotopic composition differs.

At the leading or trailing trojan point. As Thea's mass increased beyond a certain critical point it would no longer be stabilized at this point and it would enter into a 'u-shaped' orbit where it would slowly catch up to Tellus, fall into a slightly wider orbit, and fall behind again, until Tellus caught up with Thea, and then they would reverse. Eventually they would start doing something tricky like the moons of Saturn which exchange orbits every so often. At some point Thea began actually passing Tellus and then an eventual (and probably glancing) collision became inevitable. This has all been modeled pretty well, though there ARE other possibilities (a completely random collision with a Thea from some totally different part of the Solar System cannot be ruled out, but the relative velocities would then have to still imply several close passes I believe).

So, not 'on the other side of the Sun (which unintuitively is NOT a stable orbit relative to Earth), but still at the same distance and thus the composition being similar is unsurprising.

The formation of the Moon was due to a large impact; however, the body of impact was most likely a Comet. The impact resulted in: 1. Earth attaining its water; 2. The Pacific Ocean, and 3. Earth’s subduction and spreading-ridge zones. The consequences of the debris from the impact created the Moon and its gravitational effects continue the tectonic plate movements we have today.

The impact created an enormous amount of heat and energy which was released from the surface carrying with it enough solid material to later form the Moon. The material released or blown off by the steam energy and left a lower section which is the Pacific Ocean.

The Comet impacted the probably dry Earth in the region approximately 2000 km south of Japan and 2000 km east of the Mariana Trench. The force "cracked" the Earth's surface inward with the body of the Comet continuing into the Earth. The Earth's surface at the impact zone was forced into the planet causing a large dent creating subduction zones.

The consequence of this inward force caused the surface on the opposite side of the Earth to "crack" outwards creating the spreading-ridges emanating from in the Atlantic Ocean.

Study of subduction and spreading zones of the Earth reveal that they occur at almost opposite sides. Given the time span which followed the impact until today, these may vary slightly now.

The solid material blown into space from the Earth's surface had the same rotational speed as the Earth. Having insufficient energy to escape Earth's gravity this became much like a satellite with rotation. The solid material over time accreted to form the Moon and explains why the axial rotation of the Moon is the same as Earth's but it is orbiting faster.

The Moon's gravitational force on the Earth not only results in the tides of water bodies but also, to a lesser degree, tides in Earth's hot, molten magma beneath the surface. The subduction and spreading zones created by the Comet impact react predictably to the Moon's gravitational force.

A Comet consists largely of water and the enormous heat from the impact will have created superheated steam which assisted in launching solid material into orbit. The steam, however, being a gas with less kinetic energy than the solids, came under the influence of the Earth's gravity resulting in its capture closer to the surface creating an atmosphere of whatever gases were present and steam. As cooling occurred the steam condensed, fell to the surface creating the oceans.